1. FIELD OF THE INVENTION
The present invention generally relates to a closure for an opening in a building wall to isolate the interior of the building from environmental conditions outside of the building. More particularly, the present invention relates to an airtight door of the type including at least one sliding panel mounted in a guide track and supported by a plurality of rollers, sealed by a seal structure provided with a resistance type heating wire, tape or strip to establish a frost free seal. The structure disclosed is adapted for use in a door as illustrated and also is adapted for use in sliding windows or similar closures and does not require a track along the bottom of the door or window. The door or window is guided by short guides at the top and bottom of the door or window in the center of the opening and at the center of the sliding travel of the door or window. This enables a smooth threshold to be used which needs no cleaning which is a significant advantage of the invention.
2. INFORMATION DISCLOSURE STATEMENT
Various efforts have been made to provide a substantially airtight closure door or window for openings in a building wall. Weather stripping of various shapes and configurations associated with a movable closure door or window are well-known and have substantially reduced air passage past the door or window. While swinging closure weather stripping is rather effective, sliding doors and windows present additional problems due to increased frictional resistance to movement of a sliding panel which occurs when weather stripping is tightly engaged with the surfaces of a sliding door or window. The following U.S. patents are relevant to this invention but do not disclose the specific structural details.
______________________________________ 880,865 3,276,166 1,902,772 3,276,167 2,784,444 3,583,101 2,931,434 3,818,636 ______________________________________